The remarkable human capacity for visual face recognition is a cornerstone of social interaction and communication. Numerous psychiatric and neurological disorders, however, impair this critical ability. The behavioral signature of normative face perception is "holistic" processing (the whole is greater than the sum of the features) and "face-space" representation (a metaphorical coordinate system that relates the similarity of one face to another). Neuroimaging studies have identified cortical brain regions that respond to aspects of face stimuli, but it is not clear how the fundamental behavioral properties of face perception arise from the computations of neural systems. The proposed experiments will unite quantitative measures of face processing behavior with regional measures of neural activity using fMRI to provide this understanding. In Aim 1, the neural correlates of an "information processing" model of face perception are identified. The selectivity of holistic mechanisms for face stimuli, the parallel processing of visual features and the ability of the system to paradoxically improve performance with an increased workload are all behavioral features that will be described in terms of neural processes. In Aim 2, a visual adaptation method is used to test the idea that populations of neurons represent faces explicitly as deviations from an average face, and that neural representations are sharpened to allow discrimination between typical-appearing faces. In Aim 3, the effect of training and expertise is studied in terms of these neural mechanisms. Is it the case that training with an artificial stimulus set can induce face-like neural processing? The results of these studies have implications for rehabilitation and training to improve visual function, and the methods developed can be used to characterize the underlying information processing impairment in patients who have difficulty with face perception.